Disposable products have revolutionized modern lifestyle and are of great convenience to society. Such products generally are relatively inexpensive, sanitary and quick and easy to use. Disposal of such products, however, is a concern as landfills close and incineration contributes to urban smog and pollution. Consequently, there is an urgent need for disposable products that can be disposed of without dumping or incineration. An ideal disposal alternative would be the use of municipal sewage treatment plants and private residential septic systems. Products suited for disposal in sewage systems that can be flushed down a conventional toilet are termed "flushable." An essential feature of flushable products is that they must have sufficient wet strength for their intended use, yet lose structural integrity upon contact with water.
Numerous attempts have been made to produce flushable fibers, fabrics, films and adhesives that retain their integrity and wet strength during use, yet can be disposed of via flushing in conventional toilets. One approach to producing a flushable product is to limit the size of the product so that it will readily pass through plumbing without causing obstructions or blockages. Such products have high wet strength, yet do not disintegrate during flushing. Examples of this type of product include wipes such as baby wipes. This approach to flushability suffers the disadvantage, however, of being restricted to small sized articles. Many of the current flushable products are limited to such small articles.
Another approach to producing a flushable product is to manufacture a product that is normally insoluble in water, but which disintegrates in the presence of alkaline or acidic aqueous solutions. The end user is provided with an alkaline or acidic material to add to the water in which the product is to be disposed. This approach permits disposal via normal plumbing systems of products substantially larger than wipes, but suffers from the disadvantage of forcing the user to perform the step of adding the dissolving chemical to the water. A further disadvantage is that the inadvertent or unintentional disposal of such a product in a conventional toilet without the addition of the dissolving chemical can cause serious obstruction or blockage of the plumbing system. The latter disadvantage can, however, be overcome by incorporating the dissolving acid or alkali into the article but separate from the dissolvable material while in use. The dissolving chemical is only released upon contact with water during flushing.
Another approach to producing a flushable product is to prepare products such as fibers, fabrics and films from water soluble materials. Upon contact with water, the water soluble material dissolves, reducing the structural integrity of the product, and causing its disintegration, such that it will easily pass through the plumbing system. Although the products prepared by this approach are suitable for dry applications wherein the product does not come in contact with any aqueous solution, these products are not suited for applications, such as personal care products, wherein the product may come into contact with even a relatively small amount of aqueous solution.
One approach to producing thermoformable articles for use in personal care products, which can withstand prolonged contact with body fluids, such as blood, urine, and perspiration, has been the use of "ion triggerable" polymeric materials. Such "ion triggerable" polymeric materials remain stable when in contact with aqueous solutions having a relatively high ion concentration, but dissolve and disperse when placed in contact with aqueous solutions having a relatively low ion concentration, such as ordinary tap water. In other words, the polymeric materials possess "water triggerability." Ion triggerable polymeric materials have been used as binders for nonwoven webs and also as a thermoformable material. For example, a salt sensitive water soluble polyurethane binder for flushable nonwoven fabrics is disclosed in U.S. Pat. No. 4,002,171, issued to Taft. Further, a salt sensitive water soluble terpolymer for making flushable paper diapers, bandages and sanitary towels is disclosed in Japanese Patent No. JP 5125123 and U.S. Pat. No. 5,312,883 assigned to LION Corp.
A more recent approach to forming ion triggerable articles is described in U.S. patent application Ser. No. 08/730,951, assigned to Kimberly-Clark Worldwide, the assignee of the present invention. In U.S. patent application Ser. No. 08/730,951, thermoformable articles are prepared from ion triggerable materials. A preferred ion triggerable material, a copolyester which dissolves and disperses in tap water in no more than 60 minutes, offers good water responsiveness. However, the copolyester exhibits processability constraints. Typically, the copolyester has poor melt strength, is very sticky, and is very difficult to stretch into a fine fiber without breaking. Past efforts have been made to try to improve the processability of the copolyester, but have failed. The resulting fibers possess a melt strength that is not high enough to ensure good fiber processing into a desirable denier range (less than 7 denier per fiber). In addition, silicone oil based finishing agents were required to avoid the stickiness of the resulting fibers, which can affect adhesion properties of binder fibers.
What is needed in the art is a method of improving the processability of existing water-sensitive polymeric materials. Also, what is needed in the art is water-sensitive thermoformable articles having improved processability wherein the articles maintain structural integrity when exposed to ionic aqueous solutions, such as body fluids, yet readily disperse when flushed down a conventional toilet. Further, what is needed in the art is personal care products comprising thermoformable articles having improved processability wherein the personal care products maintain structural integrity when exposed to body fluids, such as blood, urine, perspiration, and other body fluids, yet readily disperse when flushed down a conventional toilet.